Measurement system with controlled pressure ramp

ABSTRACT

A measurement system and method of manufacture can include: a pressure resistant structure; a pressure inducer coupled to the pressure resistant structure, the pressure inducer having an engaged configuration, the engaged configuration of the pressure inducer increasing pressure exerted on a portion of a user in contact with the pressure resistant structure; a light source coupled to the pressure resistant structure; an optical sensor coupled to the pressure resistant structure and configured to detect a signal from the light source; a pressure sensor coupled to the pressure resistant structure, the pressure sensor configured to detect the pressure exerted on the portion of the user in contact with the pressure inducer; and a processor coupled to the optical sensor and the pressure sensor, the processor configured to correlate volumetric data from the optical sensor with pressure data from the pressure sensor and to provide a blood pressure measurement.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This claims priority benefit to all common subject matter of U.S.Provisional Patent Application No. 62/897,639 filed Sep. 9, 2019. Thecontent of this application is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

This disclosure relates to electronic physiological measurement systems,more particularly to measurement systems utilizing pressure inducers forcontrolled pressure ramps in blood pressure measurements.

BACKGROUND

The rapidly growing market for portable and wearable electronic devicesrepresents one of the largest potential market opportunities for nextgeneration biological sensors. These devices have unique attributes thathave significant impacts on their design and manufacture, in that theymust be generally small, lightweight, and rich in functionality, andthey must be produced in high volumes at relatively low cost.

One extension of the portable and wearable electronics industry is thebiological sensor industry, which includes optical sensors for measuringheart rate, blood pressure, and peripheral oxygen, for example. Thebiological sensor industry, similar to the portable and wearableelectronics industry, has witnessed ever-increasing commercialcompetitive pressures, along with growing consumer expectations and thediminishing opportunities for meaningful product differentiation in themarketplace.

Sensor system size, sensor system design, and sensor system materialsare evolving technologies at the very core of next generation biologicalsensors. These next generation biological sensors are outlined in roadmaps for development of next generation products. Competitive nextgeneration sensor systems should increase signal to noise ratio,decrease costs, and operate with increased sensor performance.Importantly, for some industry segments including wearable rings andwatches, achieving new measurements with smaller form factors andreduced power requirements is critical.

There have been many approaches to addressing the advanced requirementsof biological sensor systems and optical sensor systems with successiveconsumer product releases. Many industry road maps have identifiedsignificant gaps between the current sensor capability and designrequirements for future products.

With the advance of biological sensor systems in the wearable electronicmarket, many measurements have been incorporated into applicationsutilizing sensors onboard an electronic device. While measurementsystems, incorporated into electronic devices, can provide manyadvantages in terms of cost, time, convenience, and expanded measurementsets, many limitations still arise.

Illustratively, for example, blood pressure measurements at one timewere limited to trained professionals utilizing arm pressure cuffs.Blood pressure measurements have been incorporated into applicationsutilizing sensors onboard an electronic device. One previous approach toblood pressure monitoring is the oscillometric finger pressing method.This method utilizes an on-board photo detector and a strain gauge arrayto estimate blood pressure.

The primary limitation with the finger pressing method is controlledpressure input. Controlled pressure input can be critical to an accurateblood pressure measurement. In the finger pressing method, the pressureinput is left entirely to a user, which can lead to many inconsistenciesand indecipherable data.

As consumer electronic devices evolve to utilize and incorporate morephysiological data into medical applications and athletic applications,the pressure to push the technological envelope becomes increasinglychallenging. More significantly, with the ever-increasing complexity,the potential risk of error increases greatly during manufacture.

In view of the ever-increasing commercial competitive pressures, alongwith growing consumer expectations and the diminishing opportunities formeaningful product differentiation in the marketplace, it is criticalthat answers be found for these problems. Additionally, the need toreduce costs, reduce production time, improve efficiencies andperformance, and meet competitive pressures, adds an even greaterurgency to the critical necessity for finding answers to these problems.

Thus, a need remains for measurement systems incorporating consistentpressure inputs, at low cost, and with low power requirements. Solutionsto these problems have been long sought, but prior developments have nottaught or suggested any complete solutions and, thus, solutions to theseproblems have long eluded those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The measurement system with controlled pressure ramp is illustrated inthe figures of the accompanying drawings which are meant to be exemplaryand not limiting, in which like reference numerals are intended to referto like components, and in which:

FIG. 1 is a top isometric view of the measurement system in a firstembodiment.

FIG. 2 is a bottom isometric view of the measurement system of FIG. 1 .

FIG. 3 is a side view of the pressure inducer of FIG. 1 in a releasedconfiguration.

FIG. 4 is a side view of the pressure inducer of FIG. 1 in an engagedconfiguration.

FIG. 5 is a top isometric view of the measurement system in a secondembodiment.

FIG. 6 is an exploded isometric view of the measurement system of FIG. 5.

FIG. 7 is a top isometric view of the measurement system in a thirdembodiment.

FIG. 8 is a method of manufacturing the measurement system.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which are shown by way ofillustration, embodiments in which the measurement system may bepracticed. It is to be understood that other embodiments may be utilizedand structural changes may be made without departing from the scope ofthe measurement system.

When features, aspects, or embodiments of the measurement system aredescribed in terms of steps of a process, an operation, a control flow,or a flow chart, it is to be understood that the steps can be combined,performed in a different order, deleted, or include additional stepswithout departing from the measurement system as described herein.

The measurement system is described in sufficient detail to enable thoseskilled in the art to make and use the measurement system and providenumerous specific details to give a thorough understanding of themeasurement system; however, it will be apparent that the measurementsystem may be practiced without these specific details.

In order to avoid obscuring the measurement system, some well-knownsystem configurations and descriptions are not disclosed in detail.Likewise, the drawings showing embodiments of the system aresemi-diagrammatic and not to scale and, particularly, some of thedimensions are for the clarity of presentation and are shown greatlyexaggerated in the drawing FIGs. The term coupled is intended herein tomean a direct or indirect physical contact between elements.

Referring now to FIG. 1 , therein is shown a top isometric view of themeasurement system 100 in a first embodiment. The measurement system 100can be implemented within a wearable device or clothing item such as awatch, a ring, a finger clamp, a finger glove, or other wearable item.

Illustratively, the measurement system 100 can include a pressureresistant structure such as a band 102 and a body 104 of a watch forexample. The band 102 and the body 104 can provide a pressure resistantstructure since the band 102 and the body 104 do not readily expandoutward with increasing pressure, but instead constrain increasingpressure and exert the increasing pressure on a portion of the user indirect or indirect contact with the pressure resistant structure. Forexample, the pressure resistant structure could be a watch, a fitnessband, a ring, an in-ear surface, an accessory for a mobile phone, or acombination thereof.

The band 102 can include a pressure inducer 108 and is contemplated toprovide a non-elastic structure for constraining pressures exerted on aportion of a user in contact with the band 102, and compressing tissuebetween the pressure inducer 108 and the body 104. The pressure inducer108 is described in greater detail with regard to FIGS. 3 and 4 .

The pressure inducer 108 can provide a controlled pressure rampcontributing to, and enabling, highly accurate blood pressure readingsutilizing a wearable electronic device. The pressure inducer 108 isfurther shown to be arranged on an opposite side of the band 102 fromthe body 104.

The pressure inducer 108 can therefore provide a pressure ramp in thedirection of the body 104 where a light source, a photo detector, and apressure sensor can be arranged. In alternative embodiments, the lightsource, the photo detector, the pressure sensor, or a combinationthereof can be arranged on or formed integrally with the pressureresistant structure. Further, it is alternatively contemplated that thelight source, the photo detector, the pressure sensor, or a combinationthereof can be arranged or formed within the pressure inducer 108.

The band 102 can further include a mechanical adjustment mechanism 110to ensure a universal fit. The mechanical adjustment mechanism 110 canbe an adjustable clasp, an adjustable band, or even a screw fordecreasing an interior area of the measurement system 100.

Referring now to FIG. 2 , therein is shown a bottom isometric view ofthe measurement system 100 of FIG. 1 . The measurement system 100 isshown including the band 102 having the pressure inducer 108 oppositethe body 104 including a light source 202, an optical sensor 204, and apressure sensor 206.

The light source 202 and the optical sensor 204 can be combined tofunction as a pulse oximeter for detecting and reading volumetric fluidchanges within a user along a controlled pressure ramp. As is shown, thelight source 202 and the optical sensor 204 are both arranged within thebody 104 facing the same direction.

The light source 202 and the optical sensor 204 therefore generate areflective signal. That is, light emitted by the light source 202 isreflected and scattered by structures within the tissue of a user. Thisreflected light is then received by the optical sensor 204 as avolumetric data such as Photoplethysmography (PPG) data.

In alternative embodiments, the light source 202 and the optical sensor204 can be on different areas of the band 102 to create a transmissivesignal. With a transmissive signal, a portion of the light emitted bythe light source 202 traverses through the tissue of the user and isreceived by the optical sensor 204.

The body 104 of the wearable can further contain a processor, such as anapplication specific integrated circuit for acquiring data from theoptical sensor 204. The processor can further provide data acquisitionfrom the pressure sensor 206. In alternative embodiments, the processorcould be a remote processor.

Combined, the data from the pressure sensor 206 and the optical sensor204 can provide volumetric fluid changes at different pressure levels.The different pressure levels can be provided by the controlled ramp ofthe pressure inducer 108 through a transition temperature range.

The pressure inducer 108, can be controlled by a micro controller, andcan provide highly controlled pressure inputs for determining thevolumetric fluid change measurement at various pressure levels.Illustratively, for example, the measurement system 100 could inducepressure on a user's wrist within the band 102 with the pressure inducer108.

The measurement system 100 can detect both the pressure exerted on theuser as well as a volumetric fluid change using the pressure sensor 206and the optical sensor 204, respectively. The volumetric fluid changeand the pressure can be correlated to provide a blood pressure readingof the user.

It is contemplated that the blood pressure reading can be stored innon-transitory computer readable media within the measurement system 100and can be transmitted to another system for further processing andanalysis. For example, it is contemplated that blood pressure readingscould be shared or updated to a user's medical or training records atregular intervals.

Referring now to FIG. 3 , therein is shown a side view of the pressureinducer 108 of FIG. 1 in a released configuration. The pressure inducer108 can include a substrate 302 for providing a fixed support.

The substrate 302 can support an activation layer 304, a shape-memorylayer 306, and a passivation layer 308. The activation layer 304 caninclude a flexible, thermally conductive material having a heatingelement powered by a current supply such as a battery contained withinthe body 104 of FIG. 1 , for example.

The activation layer 304 can be controlled by a micro controller forprecisely heating the shape-memory layer 306 in terms of both heatingcycle times and heat intensities. The shape-memory layer 306 iscontemplated to be made of a shape-memory material.

The shape-memory material can be a shape-memory polymer or shape-memoryalloy. Shape-memory polymers can be engaged by increasing and decreasingtemperature, for example by the activation layer 304. The activationlayer 304 is layered on the shape-memory layer 306.

Some contemplated shape-memory polymers can also be engaged byactivating an electric field or a magnetic field. In these alternativeembodiments, it is further contemplated that the activation layer 304could be replaced by an electromagnet or electric field inducing layersformed on the top and bottom of the shape-memory layer 306. In yet othercontemplated embodiments, the light source 202 could be formed withinflexible layers of the pressure inducer 108.

For descriptive clarity, the shape-memory layer 306 will be describedwith regard to a shape-memory alloy such as an alloy ofcopper-aluminum-nickel; nickel-titanium; or zinc, copper, gold and iron.More specifically, the shape-memory layer 306 is described with regardto Nitinol, an alloy of nickel and titanium.

In the present illustrative embodiment, the shape-memory layer 306 iscontemplated to possess both shape-memory and super elastic properties.Shape-memory properties of the shape-memory layer 306 can be induced byshape-setting the shape-memory layer 306.

The shape-memory layer 306 can be shape-set by constraining theshape-memory layer 306 in a shape-set state, such as an arc, then heattreating the shape-memory layer 306 while in the shape-set state. It iscontemplated that heat treating the shape-memory layer 306 can includebringing the shape-memory layer 306 to a high temperature, such as400-550 degrees Celsius, and then rapidly cooling the shape-memory layer306.

Illustratively, for example, the shape-memory layer 306 can maintain thearc shape, of the previous example, while the shape-memory layer 306 isin a shape-set state. The shape-set state can be an austenite state. Inthe austenite state, the shape-memory layer 306 can have a volume largerthan the volume of the shape-memory layer 306 while in the deformablestate. Coupling the shape-memory layer 306 between the pressureresistant structure and a user can allow the increase in volume of theshape-memory layer 306, to create or induce pressure onto tissue of theuser. The activation layer 204 can be flexible and can follow thecontour of the shape-memory layer in the shape-set state.

Cooling the shape-memory layer 306 below a transition temperature rangecan force the shape-memory layer 306 to enter a deformable state. Thedeformable state can be a martensite state. In the martensite state, theshape-memory layer 306 can have a volume smaller than the volume of theshape-memory layer 306 while in the shape-set state. Coupling theshape-memory layer 306 between the pressure resistant structure and auser, can allow the decrease in volume of the shape-memory layer 306 tocause less pressure on tissue of the user.

The pressure inducer 108 is depicted in the released configuration ofFIG. 3 as having the shape-memory layer 306 in the deformable state.Alternatively, the pressure inducer 108 is depicted in the engagedconfiguration of FIG. 4 as having the shape-memory layer 306 in theshape-set state.

When the shape-memory layer 306 is in the deformable state, theshape-memory layer 306 can be deformed into the released configuration,which can be a flat or straight layer. The activation layer 304 can heatthe shape-memory layer 306 and place the shape-memory layer 306 backinto the shape-set state by increasing the temperature of theshape-memory layer 306 above the transition temperature range.

The shape-memory layer 306 can be placed back into the deformable stateby lowering the temperature of the shape-memory layer 306 below thetransition temperature range. Illustratively, for example, theactivation layer 304 could be turned off allowing the temperature of theshape-memory layer 306 to drop below the transition temperature bydropping back down to the body temperature of the user.

The shape-memory layer 306 differs from other materials in that when theshape-memory layer 306 is in the deformable state, atomic planes withinthe shape-memory layer 306 can be rearranged without causing slip, orpermanent deformation. It has been found in some cases that the maximumamount of deformation in the deformable state that the shape-memorymaterials of the shape-memory layer 306 can hold without permanentdamage is up to eight percent for some alloys. This compares with amaximum strain one-half a percent for conventional steels.

The transition temperature range of the shape-memory layer 306 canconsist of four temperatures, those are a martensite start temperature,a martensite finish temperature, an austenite start temperature, and anaustenite finish temperature. The martensite start temperature is thetemperature when the shape-memory layer 306 begins to change from theaustenite state to the martensite state while the martensite finishtemperature is the temperature when the shape-memory layer 306 completesthe transformation from the austenite state to the martensite state.

The austenite start temperature is the temperature when the shape-memorylayer 306 begins to change from the martensite state to the austenitestate while the austenite finish temperature is the temperature when theshape-memory layer 306 completes the transformation from the martensitestate to the austenite state. It is contemplated that the austenitefinish temperature of the shape-memory layer 306 should be above thebody temperature of about thirty-seven degrees Celsius while themartensite finish temperature should be below or at body temperature.

Referring now to FIG. 4 , therein is shown a side view of the pressureinducer 108 of FIG. 1 in an engaged configuration. The shape-memorylayer 306 is shown in its shape-set state as an arced layer. The engagedconfiguration can increase pressure exerted on a portion of a user incontact with the pressure resistant structure.

The shape-memory layer 306 can be engaged by heating the shape-memorylayer 306 above the transition temperature range with the activationlayer 304. As the shape-memory layer 306 enters the shape-set state, theshape-memory layer 306 will transition from a flat layer depicted inFIG. 3 into the arced layer of FIG. 4 .

The shape-memory layer 306 can provide enough force to bend theactivation layer 304 below the shape-memory layer 306 and thepassivation layer 308 above the shape-memory layer 306. The activationlayer 304 conforms to a shape of the shape-memory layer 306 in theshape-set state. In alternate contemplated embodiments, the activationlayer 304 could change its cross section rather than bend as a layer.

The shape-memory layer 306 can provide enough force to bend theactivation layer 304 below the shape-memory layer 306 and thepassivation layer 308 above the shape-memory layer 306. In alternatecontemplated embodiments, the activation layer 304 could change itscross section rather than bend as a layer.

That is, the activation layer 304 could be thickest where theshape-memory layer 306 extends furthest from the substrate 302 and couldbe thinnest where the shape-memory layer 306 is closest to the substrate302. In this alternate embodiment, the activation layer 304 would be incontact with both the shape-memory layer 306 and the substrate 302 whenthe shape-memory layer 306 is in the shape-set state.

The passivation layer 308 can be a thermally conductive layer forensuring the shape-memory layer 306 can cool below the transitiontemperature range to enter the deformable state of FIG. 3 . In theshape-set state of the shape-memory layer 306, the passivation layer 308is forced away from the substrate 302, and when combined with the band102 of FIG. 1 , can create pressure within the wrist of a user.

This pressure can be detected by the pressure sensor 206 of FIG. 2 andcan be correlated with pulse oximeter readings from the light source 202and optical sensor 204, both of FIG. 2 . The correlation of the pressurereadings and pulse oximeter readings can provide blood pressureestimations.

More particularly, the volumetric data can be a PPG signal having a peakoscillatory amplitude. The volumetric data can be obtained at the sametime the pressure data is obtained for a user. Illustratively, thepressure inducer can increase pressure on the user, which is detected bythe pressure sensor 206 and which changes the volumetric data of the PPGsignal detected by the optical sensor 204.

The peak oscillatory amplitude within the PPG signal is known tocorrespond to a mean blood pressure measured at the time of the peakoscillatory amplitude. A systolic blood pressure and a diastolic bloodpressure can be calculated as a ratio above and below the mean bloodpressure.

Further, the pressure detected by the pressure sensor 206 can be acontrolled ramp by carefully controlling the temperature and heating ofthe shape-memory layer 306 through the transition temperature range. Thetemperature of the activation layer 304 can be precisely controlled by amicro controller throughout the transition temperature range.

Referring now to FIG. 5 , therein is shown a top isometric view of themeasurement system 500 in a second embodiment. The measurement system500 can be implemented within a wearable device or clothing item such asa watch, a ring, a finger clamp, a finger glove, or other wearable item.

Illustratively, the measurement system 500 can include a pressureresistant structure such as a band 502 and a body 504 of a ring forexample. The band 502 and the body 504 can provide a pressure resistantstructure since the band 502 and the body 504 do not readily expandoutward with increasing pressure, but instead constrain increasingpressure and exert the increasing pressure on a portion of the user indirect or indirect contact with the pressure resistant structure. Forexample, the pressure resistant structure could be a watch, a fitnessband, a ring, an in-ear surface, an accessory for a mobile phone, or acombination thereof.

The band 502 can include a pressure inducer 508 and is contemplated toprovide a non-elastic structure for constraining pressures exerted on aportion of a user in contact with the band 502, and compressing tissuebetween the pressure inducer 508 and the body 504. The pressure inducer508 is described in greater detail with regard to FIGS. 3 and 4 .

The pressure inducer 508 can provide a controlled pressure rampcontributing to, and enabling, highly accurate blood pressure readingsutilizing a wearable electronic device. The pressure inducer 508 isfurther shown to be arranged on an opposite side of the band 502 fromthe body 504.

The pressure inducer 508 can therefore provide a pressure ramp in thedirection of the body 504 where a light source, an optical sensor, and apressure sensor can be arranged. The light source and the optical sensorcan be combined to function as a pulse oximeter for detecting andreading volumetric fluid changes within a user along a controlledpressure ramp. The light source and the optical sensor can be arrangedwithin the body 504 facing the same direction, toward the pressureinducer 508.

The light source and the optical sensor therefore generate a reflectivesignal. That is, light emitted by the light source is reflected andscattered by structures within the tissue of a user. This reflectedlight is then received by the optical sensor.

In alternative embodiments, the light source and the optical sensor canbe on different areas of the band 502 to create a transmissive signal.With a transmissive signal, a portion of the light emitted by the lightsource traverses through the tissue of the user and is received by theoptical sensor.

Referring now to FIG. 6 , therein is shown an exploded isometric view ofthe measurement system 500 of FIG. 5 . The measurement system 500 isshown with the body 504 and the band 502 being split in half.

The band 502 is shown to have a pressure inducer cavity 602 opposite thebody 504. The pressure inducer 508 can be inserted into the pressureinducer cavity 602 for rigidly mounting the pressure inducer 508 to theband 502.

Referring now to FIG. 7 , therein is shown a top isometric view of themeasurement system 700 in a third embodiment. The measurement system 700can be implemented within a wearable device or clothing item such as awatch, a ring, a finger clamp, a finger glove, or other wearable item.

Illustratively, the measurement system 700 can include a pressureresistant structure such as a band 702 and a body 704 of a ring forexample. The band 702 and the body 704 can provide a pressure resistantstructure since the band 702 and the body 704 do not readily expandoutward with increasing pressure, but instead constrain increasingpressure and exert the increasing pressure on a portion of the user indirect or indirect contact with the pressure resistant structure. Forexample, the pressure resistant structure could be a watch, a fitnessband, a ring, an in-ear surface, an accessory for a mobile phone, or acombination thereof.

The band 102 can include a pressure inducer 708 and is contemplated toprovide a non-elastic structure for constraining pressures exerted on aportion of a user in contact with the band 702, and compressing tissuebetween the pressure inducer 708 and the body 704. The pressure inducer708 is described in greater detail with regard to FIGS. 3 and 4 .

The pressure inducer 708 can provide a controlled pressure rampcontributing to, and enabling, highly accurate blood pressure readingsutilizing a wearable electronic device. The pressure inducer 708 isfurther shown to be arranged on an opposite side of the band 702 fromthe body 704.

The pressure inducer 708 can therefore provide a pressure ramp in thedirection of the body 704 where a light source 710, an optical sensor712, and a pressure sensor 714 can be arranged.

The light source 710 and the optical sensor 712 can be combined tofunction as a pulse oximeter for detecting and reading volumetric fluidchanges within a user along a controlled pressure ramp. As is shown, thelight source 710 and the optical sensor 712 are both arranged within thebody 704 facing the same direction, toward the pressure inducer 708.

The light source 710 and the optical sensor 712 therefore generate areflective signal. That is, light emitted by the light source 710 isreflected and scattered by structures within the tissue of a user. Thisreflected light is then received by the optical sensor 712.

In alternative embodiments, the light source 710 and the optical sensor712 can be on different areas of the band 702 to create a transmissivesignal. With a transmissive signal, a portion of the light emitted bythe light source 710 traverses through the tissue of the user and isreceived by the optical sensor 712.

The body 704 of the wearable can further contain a processor 716, suchas an application specific integrated circuit for acquiring data fromthe optical sensor 712. The processor 716 can further provide dataacquisition from the pressure sensor 714.

Combined, the data from the pressure sensor 714 and the optical sensor712 can provide a volumetric fluid changes at different pressure levels.The different pressure levels can be provided by the controlled ramp ofthe pressure inducer 708 through the transition temperature range.

The pressure inducer 708, can be controlled by a micro controller 718,which can provide highly controlled current from a current source 720.The current source 720 can be a battery, capacitor, or other currentsource for heating the activation layer 304 of FIG. 3 .

The micro controller 718 and the current source can together provide acontrolled pressure ramp for determining the volumetric fluid changemeasurement at various pressure levels. Illustratively, for example, themeasurement system 700 could induce pressure on a user's finger withinthe band 702 with the pressure inducer 708.

The pressure ramp, exerted by the pressure inducer, can exhibit knownsuper elastic or shape memory force displacements over a variation oftemperatures. That is, the physical shape of the shape-memory layer andamount of heat supplied to the shape-memory layer can both be used tocarefully control the pressure ramp of the pressure inducer as specifictemperatures are known to equate with the specific shape and state ofshape-memory materials.

The measurement system 700 can detect both the pressure exerted on theuser as well as a volumetric fluid change with the pressure sensor 714and optical sensor 712, respectively. The volumetric fluid change andthe pressure can be correlated to provide a blood pressure reading ofthe user.

Illustratively, for example, the volumetric data can be a PPG signalwith a peak oscillatory amplitude corresponding in time to a mean bloodpressure. That is, the pressure reading at time of the peak oscillatoryamplitude of the volumetric data, will correlate to a mean bloodpressure detected at the same time that the peak oscillatory amplitudeis measured. A systolic blood pressure and a diastolic blood pressurecan be calculated as a ratio above and below the mean blood pressure.

It has been unexpectedly discovered that this method of correlating thepressure reading to the peak oscillatory amplitude using the shapememory controlled pressure ramp allows a calibration-free, cuff-lessblood pressure measurement to be obtained due to the controllable superelastic or shape memory force displacements over a known range oftemperatures. Previous attempts required frequent re-calibrations due togreater variability in other previously used force inducing mechanisms.

The band 702 can further include a pressure plate 722 affixed to thepassivation layer 308 of FIG. 3 of the pressure inducer 708. Thepressure plate 722 can provide a larger surface area over which thepressure from the pressure inducer 708 can be distributed on the fingerof a user.

The pressure plate 722 can also provide a heat sink allowing heat fromthe shape-memory layer 306 of FIG. 3 to diffuse out of the shape-memorylayer 306 and into the pressure plate 722 allowing the shape-memorylayer 306 to cool off faster and thereby enter the deformable statefaster.

The band 702 can further be seen to include a gap 724. The gap can berelatively fixed within the rigid band 702 but could allow for minormovements or act to provide a pressure upper limit where the gap 724increases once an upper pressure threshold is reached.

It is contemplated that the blood pressure reading can be stored innon-transitory computer readable media within the measurement system 700and can be transmitted to another system for further processing andanalysis. For example, it is contemplated that blood pressure readingscould be shared or updated to a user's medical or training records atregular intervals.

Referring now to FIG. 8 , therein is shown a method of manufacturing themeasurement system. The method of manufacturing can include: providing apressure resistant structure in a block 802; coupling a pressure inducerto the pressure resistant structure, the pressure inducer having anactivation layer, and a shape-memory layer, the shape-memory layerconfigured to have a shape-set state and a deformable state, theactivation layer configured to induce the shape-memory layer into theshape-set state and increase pressure exerted on a portion of a user incontact with the pressure resistant structure in a block 804; coupling alight source to the pressure resistant structure in a block 806;coupling an optical sensor to the pressure resistant structure andconfigured to detect signals from the light source in a block 808;coupling a pressure sensor to the pressure resistant structure, thepressure sensor configured to detect pressures exerted on the portion ofthe user in contact with the pressure inducer in a block 810; andcoupling a processor to the optical sensor and the pressure sensor, theprocessor configured to correlate volumetric data from the opticalsensor with pressure data from the pressure sensor and to provide ablood pressure measurement in a block 812.

Thus, it has been discovered that the measurement system furnishesimportant and heretofore unknown and unavailable solutions,capabilities, and functional aspects. The resulting configurations arestraightforward, cost-effective, uncomplicated, highly versatile,accurate, sensitive, and effective, and can be implemented by adaptingknown components for ready, efficient, and economical manufacturing,application, and utilization.

While the measurement system has been described in conjunction with aspecific best mode, it is to be understood that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the preceding description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations, whichfall within the scope of the included claims. All matters set forthherein or shown in the accompanying drawings are to be interpreted in anillustrative and non-limiting sense.

What is claimed is:
 1. A measurement system comprising: a pressureresistant structure; a pressure inducer coupled to the pressureresistant structure, the pressure inducer having an activation layerlayered on a shape-memory layer, the activation layer conforms to ashape of the shape-memory layer in a shape-set state, and the pressureinducer having an engaged configuration, the engaged configuration ofthe pressure inducer increasing pressure exerted on a portion of a userin contact with the pressure resistant structure; a light source coupledto the pressure resistant structure; an optical sensor coupled to thepressure resistant structure and configured to detect a signal from thelight source; a pressure sensor coupled to the pressure resistantstructure, the pressure sensor configured to detect the pressure exertedon the portion of the user in contact with the pressure inducer; and aprocessor coupled to the optical sensor and the pressure sensor, theprocessor configured to correlate volumetric data from the opticalsensor with pressure data from the pressure sensor and to provide ablood pressure measurement.
 2. The system of claim 1 wherein thepressure inducer further includes a substrate and a passivation layer.3. The system of claim 1 wherein the processor is an applicationspecific integrated circuit for acquiring the volumetric data from theoptical sensor and the pressure data from the pressure sensor.
 4. Thesystem of claim 1 further comprising a pressure plate coupled to thepressure inducer, the pressure plate configured to distribute thepressure exerted on the user from the pressure inducer.
 5. The system ofclaim 1 further comprising a mechanical adjustment mechanism coupled tothe pressure resistant structure, the mechanical adjustment mechanismfor providing a universal fit.
 6. A measurement system comprising: apressure resistant structure including a band and a body; a pressureinducer coupled to the band, the pressure inducer having an activationlayer and a shape-memory layer, the shape-memory layer configured tohave a shape-set state and a deformable state, the activation layerlayered on the shape-memory layer, the activation layer conforms to ashape of the shape-memory layer in the shape-set state, and theactivation layer configured to induce the shape-memory layer into theshape-set state and increase pressure exerted on a portion of a user incontact with the pressure resistant structure; a light source coupled tothe body; an optical sensor coupled to the body and configured to detecta signal from the light source; a pressure sensor coupled to thepressure resistant structure, the pressure sensor configured to detectthe pressure exerted on the portion of the user in contact with thepressure inducer; and a processor coupled to the optical sensor and thepressure sensor, the processor configured to correlate volumetric datafrom the optical sensor with pressure data from the pressure sensor andto provide a blood pressure measurement.
 7. The system of claim 6wherein the shape-memory layer is a shape-memory polymer or ashape-memory alloy.
 8. The system of claim 6 wherein the activationlayer is configured to induce the shape-memory layer into the shape-setstate by increasing heat.
 9. The system of claim 6 further comprising amicro controller coupled to the pressure inducer, the micro controllerconfigured to control a current source for heating the activation layerand providing a controlled pressure ramp.
 10. A method of manufacturinga measurement system comprising: providing a pressure resistantstructure; coupling a pressure inducer to the pressure resistantstructure, the pressure inducer having an activation layer layered on ashape-memory layer, the activation layer conforms to a shape of theshape-memory layer in a shape-set state, and the pressure inducer havingan engaged configuration, the engaged configuration of the pressureinducer increasing pressure exerted on a portion of a user in contactwith the pressure resistant structure; coupling a light source to thepressure resistant structure; coupling an optical sensor to the pressureresistant structure and configured to detect a signal from the lightsource; coupling a pressure sensor to the pressure resistant structure,the pressure sensor configured to detect the pressure exerted on theportion of the user in contact with the pressure inducer; and coupling aprocessor to the optical sensor and the pressure sensor, the processorconfigured to correlate volumetric data from the optical sensor withpressure data from the pressure sensor and to provide a blood pressuremeasurement.
 11. The method of claim 10 wherein coupling the pressureinducer further includes coupling the pressure inducer having asubstrate and a passivation layer.
 12. The method of claim 10 whereincoupling the processor includes coupling an application specificintegrated circuit for acquiring the volumetric data from the opticalsensor and the pressure data from the pressure sensor.
 13. The method ofclaim 10 further comprising coupling a pressure plate to the pressureinducer, the pressure plate configured to thermally conduct heat awayfrom the pressure inducer.
 14. The method of claim 10 further comprisingcoupling a mechanical adjustment mechanism to the pressure resistantstructure, the mechanical adjustment mechanism for providing a universalfit.
 15. The method of claim 10 wherein: providing the pressureresistant structure includes providing a band and a body; coupling thepressure inducer includes coupling the pressure inducer to the band, thepressure inducer having the activation layer and the shape-memory layer,the shape-memory layer configured to have the shape-set state and adeformable state, the activation layer configured to induce theshape-memory layer into the shape-set state to provide the engagedconfiguration and increase the pressure exerted on the portion of theuser in contact with the pressure resistant structure; coupling thelight source includes coupling the light source to the body; andcoupling the optical sensor includes coupling the optical sensor to thebody.
 16. The method of claim 15 wherein coupling the pressure inducerincludes coupling the pressure inducer having the shape-memory layerformed from a shape-memory polymer or a shape-memory alloy.
 17. Themethod of claim 15 wherein coupling the pressure inducer includescoupling the pressure inducer with the activation layer configured todistribute the pressure exerted on the user from the pressure inducer.18. The method of claim 15 further comprising coupling a microcontroller to the pressure inducer, the micro controller configured tocontrol a current source for heating the activation layer and providinga controlled pressure ramp.